Search PubMed⌕ Search

Biomedical subjects

S K Varma

Publications and source records attributed to S K Varma.

At least 37 records · Page 2Linked to original sources
PubMed1987

Aflatoxin B1 production in orange (Citrus reticulata) juice by isolates of Aspergillus flavus Link.

Out of 7 isolates of Aspergillus flavus obtained from rotting orange (Citrus reticulata) fruits, 3 isolates were found to be toxigenic, producing variable amounts of aflatoxin B1 on a semisynthetic liquid medium. The most toxigenic isolates were further evaluated in plain juice and juice supplemented either with 0.05% yeast extract or 0.5% sucrose or both, at three different incubation periods. The maximum yield of aflatoxin B1 (162.5 micrograms/25 ml) was obtained from the juice supplemented with both sucrose and yeast extract within an incubation period of 10 days, whereas a sharp decline in aflatoxin B1 (30 micrograms/25 ml) was observed when incubation was extended beyond 10 days. The addition of yeast extract has a promoting effect on the yield of aflatoxin in comparison to the sucrose.

Aflatoxin B1↗
PubMed1987

Effects of prenatal administration of mestranol and two progestins on testosterone synthesis and reproductive tract development in male rats.

The oestrogen mestranol (0, 0.01, 0.1 mg/kg body weight per day) and the progestins medroxyprogesterone-acetate and norethisterone (0, 2, 20 mg/kg body weight per day each) in sesame oil were intubated intragastrically daily during gestational days 14.5 through 19.5 to pregnant rats. Males were studied as 20.5-day-old foetuses and 4-month-old adults for serum testosterone and LH concentrations, in vitro testosterone synthesis, anogenital distance (foetuses only) and testes, seminal vesicle and ventral prostate weights. Administration of 0.1 mg mestranol decreased by 35 to 70% basal and LH-stimulated testosterone synthesis by both foetal and adult testes in vitro (P less than 0.01). Foetal body weights (P less than 0.05), but not anogenital distances, were significantly decreased. Testosterone content in adult sera was reduced significantly (P less than 0.05) to less than 50% of control. Testes, ventral prostate, seminal vesicle and epididymal weights were unaffected by treatment. Medroxyprogesterone acetate or norethisterone administration did not alter testes endocrine function in foetal or adult offspring. In a small number of rats, pregnant for 10.5, 14.5 or 18.5 days, [3H]ethinyloestradiol was intubated and foetal and placental tissue examined for appearance and content of radioactivity. Radioactivity was detected in 10.5, 14.5 and 18.5 days old placentas, and 14.5 and 18.5 days old foetal liver, gonads and external genitalia. With [3H]medroxyprogesterone acetate, radioactivity was localized in 14.5 day placenta and foetal tissues. Thin-layer chromatographic analysis showed most of the activity to migrate as authentic ethinyloestradiol or medroxyprogesterone acetate. These results demonstrate inhibition of testicular testosterone synthesis by mestranol, presumably by being transferred across the placenta and acting in the foetus.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Cardiac function of neonates with congenital hypothyroidism before treatment.

Because of previous reports of myocardial dysfunction in adults and children with hypothyroidism, 12 newborns with congenital hypothyroidism were studied using standard electrocardiographic and echocardiographic techniques. The infants were between the ages of 7 and 28 days at the time of study. Five infants were athyrotic, and of these two had delayed skeletal maturation. Electrocardiogram revealed normal heart rates and QRS voltages in all children, while five had abnormal dome-shaped T-waves and absent ST-segments (Mosque sign). Echocardiograms were normal in all patients indicating no myocardial dysfunction or pericardial effusion. This study suggests that myocardial dysfunction is not present in the immediate newborn period of infants with congenital hypothyroidism. It is reasonable to conclude that early detection of congenital hypothyroidism by mass screening may prevent the cardiac affects of hypothyroidism as well as the other known sequelae.

Congenital Hypothyroidism↗
PubMed1985

Reproductive toxicity of 2,4-toluenediamine in the rat. 1. Effect on male fertility.

Effects of 2,4-toluenediamine (TDA) on reproduction in adult male Sprague-Dawley rats were evaluated. Diets containing 0, 0.01 and 0.03% TDA were fed ad libitum to experimental animals for 10 wk. No signs of toxicity were found. Exposure to the high dose resulted in decreased mating frequency and an increase in infertile matings. Light-microscopic examination of the testes revealed reduced numbers of sperm in the seminiferous tubules and cauda epididymides. These results indicate that TDA is capable of reducing fertility and of exerting an inhibitory or toxic effect on spermatogenesis in the rat.

Animals↗
PubMed1985

Reproductive toxicity of 2,4-toluenediamine in the rat. 2. Spermatogenic and hormonal effects.

The present study was undertaken to evaluate the endocrinologic and spermatogenic effects of 2,4-toluenediamine (TDA) in the rat. Adult male rats were fed 0,0.01, and 0.03% TDA ad libitum for 10 wk. At the end of wk 10 and at 11 wk post TDA treatment, the animals were killed, and cauda epididymal sperm counts and reproductive organ weights were determined. Blood samples were obtained for analyses of testosterone and gonadotropins. Treatment with 0.03% TDA for 10 wk reduced the weight of the seminal vesicles and epididymides and reduced serum testosterone levels. Cauda epididymal sperm counts were decreased in animals treated with 0.03% TDA for 10 wk and in TDA-treated animals placed on normal diet for 11 wk. Serum luteinizing hormone (LH) concentrations were increased and weights of epididymides and testes were reduced in 0.03%-TDA-treated animals placed on normal diet for 11 wk. The results indicate that TDA exerts a toxic effect on spermatogenesis and appears to affect androgen action and production in the male rat. Since the males exhibited reduced cauda epididymal sperm counts 11 wk after 0.03% TDA treatment, it appears that TDA induced damage to the germinal components of the testes.

Animals↗
PubMed1984

Ectopic secretion of corticotropin-releasing factor as a cause of Cushing's syndrome. A clinical, morphologic, and biochemical study.

Corticotropin-releasing factor, a hypophyseo-tropic hormone that stimulates adrenocorticotropic hormone (ACTH) secretion, has recently been isolated, characterized, and synthesized in the sheep and rat. We report on a patient with metastatic carcinoma of the prostate presenting with anterior and posterior pituitary hormone deficiency together with ACTH-dependent Cushing's syndrome. At postmortem examination, large areas of the median eminence and pituitary stalk were replaced by tumor, but the corticotrophs were markedly hyperplastic. Immunostaining of tumor cells was positive for corticotropin-releasing factor and was negative for ACTH and a wide range of other hormones. Radioimmunoassay and bioassays showed that tumor extracts and further purified fractions were active in corticotropin-releasing factor, and the tumor material coeluted with corticotropin-releasing factor on high-pressure liquid chromatography. These studies demonstrate that ectopic secretion of corticotropin-releasing factor is a cause of Cushing's syndrome in human beings. The features of this syndrome include hypercortisolism, pituitary corticotroph hyperplasia, elevation of circulating ACTH levels, and failure to suppress the pituitary-adrenal axis with exogenous glucocorticoids.

ACTH Syndrome, Ectopic↗
PubMed1983

Endocrine aspects of lithium therapy in Tourette's syndrome.

The use of Lithium Carbonate (Li2CO3) therapy in Gilles de la Tourette syndrome is reported in one patient. The patient, a 22-year-old male, was treated with a daily dose of 900 mg of Li2CO3 to attain therapeutic blood serum lithium concentration between 0.76 and 0.87 mEq/L. Renal function tests, urine analysis and thyroid function tests were monitored in addition to determinations of serum gonadotropins and testosterone concentrations throughout the 8 months of the study. The neuroendocrine measurements indicate blunting of Thyrotropin Stimulating Hormone (TSH) response, to Thyrotropin Releasing Hormone (TRH) stimulation test, which may be due to lithium therapy. The patient's growth and development were normal. This case represents the first report of blunting of TSH response to TRH in Tourette's disease. The fact that this disease has an onset during childhood suggests the importance of monitoring various endocrine functions during lithium therapy.

Adult↗
PubMed1981

Effect of intrauterine administration of antiprostaglandin drugs on implantation in the rat.

Three antiprostaglandin drugs, acetylsalicylic acid, indomethacin and ibuprofen, were administered intraluminally at different does to pregnant rats on Day 4 of pregnancy. It was observed that ibuprofen administered at a dose of 400 micrograms inhibited implantation in all rats. Ibuprofen when administered at a lower dose of 100 or 200 micrograms on Day 4 of pregnancy or at a dose of 400 micrograms on Day 3 or 5 of pregnancy did not exert such an antiimplantation effect. Acetylsalicylic acid and indomethacin also induced, but to a lesser extent, an antiimplantation effect when administered at a dose of 400 micrograms on Day 4 of pregnancy.

Animals↗
PubMed1979

Gonadotropin-like substance in the preimplanted rabbit blastocyst.

The presence of a gonadotropin-like substance in preimplanted rabbit blastocyst fluid was determined bu radioreceptorassay of human chorionic gonadotropin (hCG)/luteinizing hormone (LH), using receptors prepared from bovine corpus luteum, rat testis, and rat ovaries. An average of 16.6 microliter of fluid containing 0.83 ng of luteotropic material was recovered from each blastocyst. An intense fluorescence was exhibited by the trophoblastic cells of the blastocysts treated with fluorescein-conjugated gamma-globulin isolated from antiserum raised against human chorionic gonadotropin. Serum concentrations of LH as well as estradiol, progesterone, and 17 alpha-hydroxyprogesterone up to day 6 after mating were determined in pregnant rabbits and compared with those in pseudopregnant and normal rabbits. In pregnant rabbits after mating, a surge of 62 +/- 15 ng of luteinizing hormone and 73 +/- 22 ng of progesterone/ml of serum occurred which returned to basal levels at 6 hours and on day 1, respectively. Secondary increases in serum luteinizing hormone of 26 +/- 12 to 36 +/- 16 ng/ml on days 3 and 5 and in serum progesterone of 16 +/- 4 and 14 +/- 5 ng/ml on days 5 and 6, respectively, were observed in pregnant rabbits.

Animals↗
PubMed1979

Long-term perspectives of thyroxine administration in neonatal rats.

Newborn pups were injected with normal saline (group A) and exogenous thyroxine (group B). Elevated T4 and decreased TSH levels from day 7 in group B continued until day 35. T4 and TSH were in normal range by day 42 and were similar to group A. Weight gain was significantly lower in group B. On day 45, half hourly injections (subcutaneous) of TRH were given to half of group A and group B each. Remaining halves were injected with saline. TSH response to TRH was significantly decreased in group B rats. Thus, neonatal hyperthyroidism results in (1) permanent decrease in pituitary reserve of TSH secretion and (2) a permanent imprinting regarding growth and thyroidal development and thus, neonatal period is critical for thyroidal development.

Animals↗
PubMed1979

Ratio of amniotic fluid cortisol and maternal serum cortisol (AFC/MSC) as an index of fetal lung maturity.

Fifty-eight samples of amniotic fluid from pregnant women between the gestation period of 34-42 weeks were analyzed for total cortisol levels. Thirty-four simulatneous maternal serum total cortisol levels were also measured. Amniotic fluid cortisol (AFC), maternal serum cortisol (MSC) and the ratio of AFC/MSC were correlated with L/S ratio. AFC alone and AFC/MSC ratios correlate with L/S ratios (r=0.36, p less than 0.01, and r=0.46, p less than 0.01, respectively). MSC and L/S ratios had no correlation. AFC/MSC had less individual variation as compared to AFC alone. The AFC/MSC could be divided by an arbitrary line at 0.1 and values less than 0.1 signify immature fetal lungs. Values of 0.1 and greater signify mature fetal lungs.

Amniotic Fluid↗